The present invention relates generally to golf club heads and, more particularly, to golf club heads having a face plate of variable thickness.
Modern golf clubs have typically been classified as either woods, irons or putters. The term “wood” is an historical term that is still commonly used, even for golf clubs that are constructed of steel, titanium, fiberglass and other more exotic materials, to name a few. The woods are now often referred to as “metal woods.” The term “iron” is also an historical term that is still commonly used, even though those clubs are not typically constructed of iron, but are rather constructed of many of the same materials used to construct “woods.”
Many advancements have been achieved, particularly over the past couple of decades, to make it easier to hit longer and straighter shots with woods and irons. In general, golf clubs are now designed to be more forgiving, so that shots that are struck less than perfectly will still have fairly consistent distance and directional control. Moreover, club heads now are commonly constructed of combinations of materials, to attempt to optimize the ball flight desired by a particular type of player.
One particular improvement that relates especially to metal woods is the use of lighter and stronger metals, such as titanium. A significant number of the premium metal woods, especially drivers, are now constructed primarily using titanium. The use of titanium and other lightweight, strong metals has made it possible to create metal woods of ever increasing sizes. The size of metal woods, especially drivers, is often referred to in terms of volume. For instance, current drivers may have a volume of 300 cubic centimeters (cc) or more. Oversized metal woods generally provide a larger sweet spot and a higher inertia, which provides greater forgiveness than a golf club having a conventional head size.
One advantage derived from the use of lighter and stronger metals is the ability to make thinner walls, including the striking face and all other walls of the metal wood club. This allows designers more leeway in the positioning of weights. For instance, to promote forgiveness, designers may move the weight to the periphery of the metal wood head and backwards from the face. As mentioned above, such weighting generally results in a higher inertia, which results in less twisting due to off-center hits.
There are limitations on how large a golf club head can be manufactured, which is a function of several parameters, including the material, the weight of the club head and the strength of the club head. Additionally, to avoid increasing weight, as the head becomes larger, the thickness of the walls must be made thinner, including the face plate. As the face plate becomes thinner, it has a tendency to deflect more at impact, and thereby has the potential to impart more energy to the ball. This phenomenon is generally referred to as the “trampoline effect.” A properly constructed club with a thin face can therefore impart a higher initial velocity to a golf ball than a club with a rigid face. Because initial velocity is an important component in determining how far a golf ball travels, this is very important to golfers.
It is appreciated by those of skill in the art that the initial velocity imparted to a golf ball by a thin-faced metal wood varies depending on the location of the point of impact of a golf ball on the striking face. Each face plate has what is referred to as a “sweet spot.” Generally, balls struck in the sweet spot will have a higher rebound velocity. Many factors contribute to the location and size of the sweet spot, including the location of the center of gravity (CG) and the shape and thickness of the face plate.
Manufacturers of metal wood golf club heads have more recently attempted to manipulate the performance of their club heads by designing face plates of variable thicknesses. Because of the use of lightweight materials such as titanium for the face plate, a problem arises in the stresses that are transmitted to the face-crown and face-sole junctions of the club head upon impact with the golf ball. One prior solution has been to provide a reinforced periphery of the face plate in order to withstand the repeated impacts. The manufacture of face plates has typically been accomplished by forging a metal, such as a titanium alloy, to achieve the face thickness variation.
Another approach to reduce these stresses at impact is to use one or more ribs extending substantially from the crown to the sole vertically across the face, and in some instances extending from the toe to the heel horizontally across the face. Because the largest stresses are located at the impact point, usually at or substantially near the sweet spot, the center of the face is also thickened and is at least as thick as the ribbed portions. However, these club heads fail to ultimately provide much forgiveness to off-center hits for all but the most expert golfers. The variable face thickness design and the use of titanium face inserts have also recently been applied to iron golf club heads with similar disadvantages and limitations. Well known casting and forging techniques have typically been employed to achieve the variable face thickness designs for irons.
It should, therefore, be appreciated that there exists a need for an improved method of manufacturing golf club face plates that exhibit greater forgiveness across a substantial portion of the face plate while continuing to impart higher initial velocity having a variable thickness. The present invention fulfills that need and others.